Snap acting drum switch



Oct. 15, 1957 P, HUTT SNAP ACTING DRUM SWITCH 2 sheets-sheet 1 Oct. 15,1957 P. HUTT 2,810,029 l SNAP ACTING DRUM SWITCH 2 Sheets-Sheet 2 FiledFeb. l, 1956 means.

2,810,029 Patented "Oet- 15, 1957 United States Patent *,*Oftice l,SNAPACTING .DRUM `SWITCH Philip Hutt, Milford, Conn., assigner to GeneralElectric Company, a corporation of New York Y The `present invention'relates kto an electric switch and particularly to a reversiblesnapacting drum switch that is particularly adapted to bemounted on thestandard or column .o f aportable lamp for'controlling the severalcircuits thereof.

The great majority of portable `lamps in use today are provided with acombined lamp socket and switch either of the turn knob or pull chaintypes which are hidden from view bythe lamp shade. There are also manyfloor lamps -where the fturn 'knob switch is separate from the lampsocket but again it is hidden by the lamp shade. In an attempt toincrease the ease of operating portable lamps, switch designs have beenconceived for either the base of the lampor the column of the lamp sothat it will 'be out from under Athe lamp shade `and clearly in view.

The novel drum switch of the present invention i s 'believed Vto beimprovement over other switch mechanisms in the prior art,gbecauseitisboth reversible in that it canbe turned either clockwise orcounterclockwiseand the contacts are quick acting so that this switch isusable in b oth A. C.' and 1D. C. circuits. The basic elements o f myinvention include a yfirst 'switch member ortubular base Yhaving aseries o f ratchet teeth, several o f which are current carrying tocomprise the iixed contacts' of the switch, and a second switchvmemberordium which is relatively rotatable with respectto the firstabout the vertical centerline o f .the switch, and has a similar seriesof ratchet teeth but inclined in the opposite direction- Most of theratchet teeth of this second series are joined together and are currentcarrying to comprise the movable contact of the switch. vinterposedbetween the two series of ratchet teethis a third intermediate memberconsisting of an insulating washer supporting a series of contactingpawls which are symmetrically arranged above and below the washer forengaging the ratchet teeth ofthe two switch members. Thus,v as thesecond switch member is rotated in one direcfon with respect to the irstswitch member, ,the top pawls of the intermediate member will becomelocked with respect vto the second switch member while the bottom pawlswill sweep the ratchet teeth of the first switch member. Then as thesecond switch member is rotated in the opposite direction, Athe bottompawls of the intermediate member will become `stationary with respecttoethe ratchet teeth .of the iirst switch member and sweep the ratchetteeth of the second switch member. The series of pawls of theintermediate mem` ber serve the dual function vof connecting the movablecontact with the `fixed contacts of the switch while also serving toindex the movement of the switching elements. The principal ,object ofthis invention is to provide a drum switch Iwith a reversible snapacting mechanism'.

A Afurther object of this invention is to provide Va reversible snapactingdrum switch with a suitable ,indeinng Aifurtherobject ofthisinvention is to providea rev ers 'i. ble snap acting drum switchwith an intermediate member containinga series of contacting pawlswhichare pivotally mounted onan insulating washer to connect the movable`contact with theixed contacts ofthe switch.

A still further object of the present `invention is to provide areversible snapV acting drum switch lwith two series of ratchet teeth,theiirst series containing the fixed contactsof the switch while thesecond series includes the movable vcontactor of the switch, all ofwhich are adapted to be joined together by an intermediate member containing a series of. contacting pawls that also serve the function ofan indexing means;

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawings and its scope'will bepointed out in theappended claims. t

Figure 1 is an elevational view of atypical table lamp having mountedkon its column a drum switch embodying my ,inventiva Figure 2 is` anenlarged view `of the drum switch of Figure l shown separated from thelamp.

Figure 3 is an exploded view showing in detail the varions elements ofmy invention.

Figure 4 is a cross-sectional elevational view .of the switch of Figure2 talen on its vertical center line.

Pignre 5 is a cross-sectional view showing the method .ef fastening theassembly Washers te -thesplit bushing for supporting the switch inalamp. f Y

, Figure .61s ,detailed Showing ef befhlhe neieh ,itl .the edge oftheinsnlating washer ofthe in termediate`inember and the contacting pawlwhich is to be supported therein.

Figure 7 is an assembled View showing the contacting pawll of Figure `6supported in the notch of the insulating washer.

Figure 8 is a diagrammatic showing of thefol positionto'r the switch`with the two series o'f ratchet teeth conaining the xed and movablecontacts of Athe switch as they are bridged by the contacting ,pawls ofvthe intermedi.- atte' membe'r. i

1Figure 9 has additional diagrammatic showings ofthe different positionsofthe switch when lthe top member .orldrurn is rotated in a clockwisedirection or to the left through the low, medium and -high positions ofthe switch.

Eignre 1 0 is a diagrammatic showing Aof Ythe wiring arrangement of aportable llamp including a three-way lamp socket and andrum switchembodying my-invention.

Figure l-l is a bottom plan view of `the rotating'drum of thes'witchshowing the single movable Vcontactassernbled therein with relation'tothe pair of molded ratchet teeth ofthis member. Figure 12 is -a -topplan view of the tubular base of therswitch showing the angulardisposition of Vthe :fixed con'acts of the switch with respect to theother vratchet teet Referring :in detail to the drawing, Figure 1 showsa table :lamp 10 including a supporting base 11, a colnmn 1 2` and adecorative husk -13 for containing the vscrew shell socket of `the lamp.The lamp shade 1.4vis usually translucent which `makes it difficult tofind `tliensnal turn knob or push `through switch if `it is combinedwith the lamp socket. VMy invention is embodiedV in the drum switch 15assembled in the column 1 2 o f `the -lampfor controlling fthe lightingcircuits of the lamp.

Turning now to `a consideration of the specific details of `the switchin Figure 3, the supporting Amember of the switch elements is a splitmetal ybushing 20 which is internally threaded at both ends `so that theswitch may be fastened tothe conventional wiring pipesor conduits (notshown) of theglam'p. Thesepipesareghidden from sight `by the two piecesof deeerativeztubing 16 `.and

i 17 that are assembled between the switch and the lamp v,2,810,029 t Ybase 11 and between the switch and the husk 13, respectively. Alongitudinal split 21 is provided so that the bushing may be temporarilycollapsed to reduce its diameter and a pair of assembly washers 22slipped over the ends. The outer surface of the bushing has two rings ofradially spaced projections or embossings 23 which are arranged in pairsto form clamping lips at both ends of the bushing for engaging thewashers 22. Looking for a moment will be understood that when thediameter of the bushing is reduced, each washer 22 may be forced overthe end of the bushing until it is confined in the ring between thepairs of embossings 23 and held firmly in place. While the method ofmounting the drum switch of this invention is being described in detailherein, it is deemed to be a separate invention from that of the switchmech- Vanism; therefore, it is being claimed in my copending applicationSerial No. 562,799 filed simultaneously with this application andassigned to the same assignee asis the present invention. Y v

Looking at Figure 3, the present switch comprises two main switchmembers, namely, the tubular base 25`which 'is mounted on the bushing20, and the drum 26 that is at Figure 5 of the drawing, it vtelescopically arranged over the base to enclose the switching elements.In the preferred form of my invention both the base and the drum aremolded of a suitable insulating material such as melamine, urea, or thelike. Base 25 includes a series of upwardly facing ratchet teeth 27arranged at the foot of the hub portion 28. The inner f surface of thetop of the drum 26 has a similar series of ratchet teeth formed by thesplit brass ring 29 having teeth 30 which are Vopposed to the ratchetteeth 27 of the base by being inclined in the opposite direction. The

ring 29 is mounted within the drum so that the split vportion isseparated by a single ratchet tooth 31 that iS a molded portion of thedrum as seen in Figures 8 and ll for continuing the configuration of theratchet teeth around the entire inner surface of the drum. The side ofthe ring 29 which is opposite the split is undercut as at 32 in Figures3 and 8 so that a single molded ratchet tooth 33 similar in shape to thetooth 31 replaces the usual ratchet tooth of the ring 29. The insulatedratchet teeth 31 and 33 of the drurn provide the two off posi- Ations ofthe switch, while the single split ring 29 contains two groups ofratchet teeth 30, there being three teeth in each group providing the1ow, medium and high` positions of the switch.

Going back to a consideration of the ratchet teeth 27 of the base '25,as seen in Figure 3, several of the teeth are replaced by contactingelements 34 which when mounted in the base represent the fixed contactsof the switch. Lead wires 35 are crimped or otherwise fastened (to thecontacts for connecting them in the lamp circuit. As best seen in Figure4, the lower interior of the base 25 is cut away as att36 so thatthe'contacts 34 with the lead wires 35 attached may be inserted thereinwith each contact being held in place in a narrow opening 37 thatextends outwardly of the base. Each contact 34 is assembled in the baseby bending or staking the side edges of the contact inwardly toward thecentral axis of the base so that the contact may not be withdrawn by apull exerted on the lead wire 35. The means for securing the lead wire35 on the shank end of the contact prevents it from moving up out` ofthe base, so that the con- 'tact is rigidly fastened inthe base. Thereare in effect eight ratchet teeth in the drum, namely, the six teeth 30of the movable contact 29 andthe moldedteeth 31 and 33, so that in asimilar manner there would be eight ratchet teeth in the base. However,there are three fixed contacts 34 mounted in the base so that betweentwo of the contacts there is but a single molded ratchet tooth whilethere are two such molded teeth separating the third contact from thefirst two mentioned contacts.

' As discussed previously, the tubular base 25 is to be fixed on thebushing 20. This is done by` supporting the 4 base on the lower washer22 from turning with respect to group of three longitudinally theinterior of the circular opening 39 that extends through the base. Thereis a sliding fit between the opening 39 of the base and the bushing 20and the embossments 23 of the bushing are seated within the grooves 38in the base to prevent the relative rotation of these parts.

One of the most important elements of this invention is the intermediatemember 40, now to be discussed, that is interposed between the twoseries of ratchet teeth on the base and on the drum for connecting themovable contact 29 with the fixed contacts 34. The use of thisintermediate member provides this switch with a reversible snap action,as well as a uniform indexing means in all positions of the switch. Theintermediate member 40 is constructed out of a thin insulating washer 41of fiber material that is adapted to slip over the hub 28 of the base25. As best seen in Figures 6 and 7, the peripheral edge of the washer41 has a series of notches 42 formed therein with a restricted opening43 at the very edge communicating with the larger portion which isgenerally of rectangular shape. A contacting pawl 44 of thin, springstrip material such as phosphor bronze is adapted to be supported by aquick slip-on assembly and preventing the base the bushing by forming aextneding grooves 38 on vmethod in the notch 42 of the washer so thatthe washer tion 47 are spaced apartrby a distance substantially equal tothe thickness of the washer 41 to provide a close sliding fit betweenthese parts. The inner edge of the base 48 of the U-shaped portion 47has a spring locking tongue 49 that is bent back upon itself for holdingthe pawl 44 on the washer. Looking now at Figure 7, it will beunderstood that the pawl 44 is in its assembled position on the washer41 and the locking tongue 49 is seated behind one of the lips 50 whichserve to form the restricted opening 43 in the edge of the washer.Although only one lip 50 is needed to lock the pawl 44 in the washer,the notch 42 is made symmetrical so that the washer is identical on bothsides and the operator 'in assembling the switch need not spend timedetermining the correct side of the washer. Y The pawl 44 is capable ofa slight pivotal action with respect to the washer 41 since thesupporting portion 47 of the pawl may slide back and forth on the washerlin a radial direction when the locking tongue 49 is compressedslightly. The advantage of this freedom of action is that the pawls 44will adjust themselves to the space between the molded base and drum.The contacting pawls 44 could, of course, be riveted or otherwiserigidly fastened to the Washer but this would require a high degree ofaccuracy in forming and positioning these parts to prevent binding orinterference between the pawls 44 and the molded base or drum. Also,riveting would be a more expensive method than the slip-on assemblypreviously mentioned. i

Now that all ofthe structural details of this switch V have beendescribed, attention will be given to the nature intermediate member 40is shown. as-arranged between the base and the cover and is representedby the insulating washer 41 and the series of contacting pawls 44.

Figure l is a wiring diagram showing'the drum switch I embodying myinvention connected inl a circuit for controlling a three-way lampsocket 53. The power supply cord includes the attachment plug 54 andconductors 55 and 56. One side of the line, conductor 55, is `connectedwith the center fixed contact 34 designated Line in Figure 8, while theother conductor 56 extends completely through the switch 15 and isconnected with the screw shell (not shown) of the socket 53. A three-waysocket is of well-known construction in this art and is for use with atwo filament lamp that is capable of giving `three degrees ofillumination. Each filament is of dififerent size to give varyingdegrees of light so that the :smallest lilament gives one degreeoflight, thezlarger filament givesanother degree and then the combinationof the two give a third degree of light. Such a three-way socketcontains two Vcenter contacts (not shown) which ,are connected by meansof conductors 57 `and 58 to the two outer fixed contacts 34 in the basedesignated 1 and 2.

Thus, the circuit is complete, but as the switch is shown in Figure 8,it is in the olf position since the 'circuit is broken by the contactingpawl 44 engaging lthe central ixed contact 34 designated Line which isalso engaging the molded insulating ratchet tooth 33 of the drum. lIf inAplan view the drum were rotated clockwise, it would in Figures 8` and 9move from right to left. This is actually what is shown in Figure 9wherepthere are three diagrammatic views of the switch positions low,medium and high At the top of the figure the movable contact'ig hasmoved one notch Ato the left so that the circuit is complete from theline to the central fixed contact 34 through one of the contacting pawls44 to the movable contact 29 and Vback through another contacting pawl-44 to the left-hand iixed contact 34 and `then through the socket, `thelamp, and then backthrough the screw shell to the source of energy. Itwill be noted Vthat the insulating ratchet tooth 31 of the drum 26 isaligned `with the right-hand ixed contact 34 so that only a single filament of the lamp bulb would be energized. In themiddle diag-ram ofFigure `9 the movable contact 29 has moved another notch to the left sothat the circuit extends from the central fixed contact 34 through tothe movable contact 29 and then back to the right-hand fixed contact 34.Likewise, in the 'bottom diagram of Figure 9, the movable Contact 29 hasmoved a further notch to the left confiecting all of the fixed contactsin the circuit to give .the maximum illumination of the lamp bulb. t n

Going back again to Figure 8 for a consideration Y.of the action of theVintermediate member 40, it should be noted Vthat the arms 45 of thecontacting pawl 44 extend outwardly inthe same direction, namely to theright, in asymmetrical manner with respect to the washer 41. Thus, asthe drum is rotated clockwise inplan view,.it will move to the left inVFigure 8, but since the free end ofthe upper arms 45 of the pawl 44engage the vertical risers of theratchet teeth of the drum, theintermediate member will be carried along with it. However, since thebase y25 is rigid with respect to the bushing 20 and thus the entirelamp 10, it should be understood that the lower arms 45 of thecontacting pawl 44 will sweep the ratchet teeth 27 'as well as Vthefixed contacts 34 of the base. This is true .because the ratchet teethof the base are opposed to the complementary ratchet teeth of the drumso that as .the intermediate member 40 moves to the left orclockwise,'the lower arms 45 of the contacting pawl 44 merely slide overthe inclined surfaces of the ratchet teeth and doLnotengage the verticalrisers thereof.

4In considering the action of the switch when the drum is lturned in theoppostie direction, lnamely counterclockwise, it will be understood thatthe relationship between the ratchet teeth .of :the drum and the'intermediate memlier has been reversed. The intermediate member 40 cannoflonger move with the drum which would in Figure 8 kbe 'from left to.right since the lower arms 45 Aof the pawls engage the vertical risersof the Vratchet teeth '27 and of the base 25. Hence, the intermediatemember is stationary with respect to the base 25 while the upper arms 45of the contacting pawl 44 are swept by the ratchettee'th 31 and 33 ofthe drum as well as ratchet teeth 30,0f the single movablecontact 29.Since the intermediate `meinber 40 is freely oating in` thatit may shiftvertically on the hub 28 of the base 25, itis an interestingphenomenonthat the arms 45 of the contacting pawl 44 are deected by substantiallyequal amounts whenever the drum is rotated. Thus, when there is acompressive -force tending to deiiect the arms` on one side of thelinsulating washer 41, that force is likewise carried into thevcomplementary portions of the contacting .pawls so Vas to reduce themaximum stress` exerted on any portion :of 'the pawls. As `a result, allofthe pawls arestressed simultaneously to ugive both a uniform switchingaction and long lifeto the c ontacting parts. The contacts are alsovkept clean from oxidation yand dirt formations that might collect dueto Y the wipingaction afforded by the pawls of the `intermediatemember.- i

Having described my invention of a rotating drum switch that :iscapableof lbeing mounted on the column of a portable lamp, it will bcwell understood by those skilled in this `art that this switch isreversible in that ythe outer drum or `actuating member may be turnedveither clockwise or countercloclwise. Ivf the lamp is to be used mostlyat thehighest degree of illumination the switch can be turned onernotchfrom `pff to high` rather than going in the reverse direction throughlow and rnedium t0 highf" 4 Y v v Furthermore, this switch has vquickmake 'andbreak contacts because-of the use of the snap-acting springpawls which cooperate with the two series 'of ratchet teeth in the baseand drum. `Since all of the pawls `are stressed simultaneously, theygive the switch an excellent rsmooth and uniform feel during thechanging `of the position of the switch. While I have chosen to useeight ratchet Yteeth in both the base and drum, it is recognized thatother groupings which are multiples of four may also be selected. Eightteeth were'chosen in the preferred embodiment because of the particularangle of inclination of the ratchet teeth which Aresulted. Although thisangle is not critical, it should be `large enough to provide a positiveindexing force tending to hold the drum in a predetermined location foreach position of the switch. This means that the drummay notbe turnedsothatthe pawls engagefand are hung on the very tips of the ratchetteeth of either the base orA the drum. The forces stored `in the springpawls 44 tend to return the drum `to the position shown in Figure `8when the hand `is removed from the drum.` x

Those skilled in this art will immediatelyrecognize that my inventiondeals with the particular `combination yof two series of ratchet teethcontaining the movableand fixed contacts respectively which `are joinedby `an inter.- mediate member that supports a group of spring pawls. Mypreferred embodiment placesthese Velements .in a stacked relationship ofbase, intermediate member and drum reading from bottom to top. However,I appreciate these same `elements could be `combined -in concen- -tricring fashion with the opposed `ratchet teeth either such as the top withthe intermediate member covered thereover and again bridging the movableand fixed contacts. Likewise, the parts could `be `reversed by formingthe intermediate member with ratchet teeth `.while Athe movable andfixed contacts comprise spring pawls `to give a similar switchingaction.

Other wiring arrangements of my switch yin a pQrtable lamp will, ofcourse, beevident depending on whetherqthe switch fis to be wireddirectly to lthe' lamp socket .or fto ,a junction block that may eitherbe in the supporting base operation that recommend 7 of the lamp or nearthe socket. The present drum switch has many desirable features as tocost, appearance, and i its use in portable lamps but it could also beadapted for small fans and appliances as 'well as wall mounted houseswitches for controlling Vthe lighting circuits.

Itis important to note that while I have chosen to illustrate myinvention with edgewise contacts, an alternate construction wouldinclude atwise contacts seated on the inclined surfaces of the ratchetteeth.

Modifications of this invention will occur to those skilled in this artand it is to be understood, therefore, that this invention is notlimited to the particular embodiments disclosed but that it is intendedto cover all modifications which are Withn'; the true spirit and scopeof this invention.

What I claim as new and Patent of the United States is:

1. A reversible snap acting rotary switch comprising a first switchmember with a series of ratchet teeth, some ofwhich arecurrent-carryingand constitute the fixed contacts of the switch, a second switch memberalso hav- 'ing a series of ratchet teeth, some of the second series ofratchet teeth being current-carrying and joined together to form themovable contact of the switch, and a third member of insulating materialpositioned in operative relation with said first two members andsupporting a plurality of spring contacting pawls of conductive materialfor wiping engagement with the two series of ratchet teeth so that uponrotation in one direction of the second switch member, the third memberwill become stationary with respect to the first switch member while thepawls will sweep the teeth of the second switch member, and uponrotation of the second switch member in the opposite direction, thethird member will be driven in the reverse manner. p

2. A reversible snap acting drum switch comprising a base member with aseries of ratchet teeth, some of which are current-carrying, a drummember also having a series of ratchet teeth, `some of which arecurrentcarrying and joined together to form the movable contact of theswitch, and an intermediate member of insulating material supporting aplurality of spring contacting pawls of conductive material for wipingengagement with the two series of ratchet teeth so that upon turning thedrum in one direction, the intermediate member will become stationarywith respect to the drum while the pawls will sweep the ratchet teeth ofthe base member, and upon turning the drum in the opposite direction,the intermediate member will become stationary with respect to the basewhile the pawls will be swept by the ratchet teeth of the drum.

3. A reversible snap acting rotary switch comprising a first stationaryswitch member with a series of ratchet teeth, some of which arecurrent-carrying and constitute the fixed contacts of the switch, asecond switch member also having a series of ratchet teeth but opposedto th-e teeth of the rst series, most of the ratchet teeth in the secondseries being current-carrying and joined together to form the movablecontact of the switch, and a third intermediate member of insulatingmaterial supporting a plurality of spring contacting pawls of conductivematerial, each of which extend on opposite sides thereof for wipingengagement with the two series of ratchet teeth, so that upon rotationof the second switch member in one direction, the intermediate memberwill become stationary with respect to the second switch member whilethe pawls will sweep the teeth of the first switch member and uponrotation of the second switch member in the opposite direction, theintermediate member will operate in the reverse manner.

4. A reversible snap acting rotary switch comprising a tubular base ofinsulating material with a cylindrical hub and a series of ratchet teethcircumferentially arranged around the hub at one end thereof, severalfixed desire to secure by Letters electrical contacts representing someof the alternate ratchet teeth, and an insulating washer mounted on thehub supporting a plurality of individual V-shaped spring pawls eachsupported at their centers on the washer, and a rotating drum ofinsulating material telescopically arranged over the hub to enclose theelectrical switching elements, the inner surface of the top of the drumhaving a series of ratchet teeth most of which are joined together to becurrent-carrying and representing the movable contact of the switch,whereupon rotation of the drum in one direction will rotate theinsulating washer so that the pawls will sweep the ratchet teeth of thebase, and upon rotation of the drum in the opposite direction, thewasher will be held stationary with respect to the base and the ratchetteeth of the drum will sweep the spring pawls.

5. A reversible snap acting rotary switch comprising a rst switch memberof insulating material having a series of ratchet teeth arranged in acircular manner, several of the alternate teeth being of conductivematerial and representing the fixed contacts of the switch, a secondswitch member of insulating material having a similar series of ratchetteeth but extending in the opposite direction, most of the ratchet teethof the second series being of conductive material and joined together torepresent the movable contact of the switch, and an intermediateinsulating member freely iloating between the two switch members andsupporting a plurality of spring pawls which are adapted to complete thecircuit between the movable and fixed contacts in such a manner thatupon rotation of one of said members in one direction, the intermediatemember will be driven by the moving member so that the pawls will sweepthe ratchet teeth of the other member, and when the movable member isrotated in the opposite direction, a reverse operation will take'place.

6. A reversible snap acting rotary switch comprising a first switchmember of insulating material having a series of ratchet teeth arrangedin a circular manner on one face thereof, several of these teeth beingformed of conducting material and representing the fixed contacts of theswitch, and a second switch member of insulating material supporting asplit metal ring having a similar series of ratchet teeth but inclinedin the opposite direction from the first series, said second memberbeing telescopically arranged over the iirst switch member to rotateabout a common vertical axis, and a freely rotatable intermediatecontacting member including an insulating support piece carrying aplurality of V-shaped spring contacting pawls which are insulated fromeach other to connect the ratchet teeth of the movable contact with thefixed contacts of the first switch member, so that upon the relativerotation of the second switch member in one direction, the pawls of theintermediate contact member will become stationary with respect to themoving member while they will sweep the Contact of the other switchmember, and the reverse would be true upon the rotation of the movableswitch member in the opposite direction.

7. A reversible snap acting drum switch having a base member with acircular ratchet surface, some of the alternate teeth of which are ofconducting material to serve as the fixed contacts of the switch, a drumsupporting a single contact member having a series of ratchet teethwhich are opposed to the rst series of ratchet teeth, said drum beingrelatively rotatable with respect to the base so that the single contactmember represents the movable contact of the switch, and an intermediaterotatable member of insulating material supporting a series of V- shapedspring contacts comprising pawls for connecting the movable with the xedcontacts while also serving as an indexing means so that the rotation ofthe drum in one direction will drive the intermediate member with thepawls of the intermediate member sweeping the ratchet teeth of the base,while if the drum were to be rotated in the opposite direction, theintermediate member would become stationary with respect to the base andthe pawls of the intermediate member would be swept by the ratchet teethof the movable contact.

8. A reversible snap acting drum switch comprising a tubular bushinghaving supported thereon a stationary base member of insulating materialwith a continuous ratchet surface, several of the teeth of which are ofconducting material and represent the fixed contacts of the switch, anda hollow drum of insulating material telescopically arranged on the saidbushing to overlie the base member, a single metal contact member havinga series of ratchet teeth supported within the drum in opposed relationto the iirst series of ratchet teeth on the base, said contact memberconstituting the movable contacter of the switch, and a rotatableintermediate contacting member comprising an insulating washersupporting a series of V-shaped contacts which'arel symmetricallyarranged on the top and bottom of the washer to connect the movable andthe fixed contacts for controlling different circuits through theswitch.

9. As an article of manufacture an intermediate contact member for anelectric switch comprising an insulat 10 ing washer having a series ofnotches formed in the outer peripheral edge thereof, and a V-shapedspring contact having a locking tongue at its apex which is mounted inthe notch with the tongue bearing against the opposite side of the notchin cooperation with an inwardly facing lip formed at the mouth of thenotch whereby the spring contact is pivotally supported on the washer.

10. As an article of manufacture an intermediate contact member for anelectric switch comprising an insulating washer having a series ofnotches, each formed in the edge thereof for supporting a V-shapedspring pawl that is symmetrically arranged with respect Vto the washer,and a spring locking tongue extending from the apex of each pawl andengageable with an opposing wall of the notch.

References Cited in the le of this patent UNITED STATES PATENTSV1,138,763 Klein May 11, 1915 2,136,369 Belcher July 9, 1937 2,163,864Bissen oct. 12, 1931

